Electrical Machines Field weakening control method is used for the _________ ? above rated speed below rated speed None of these both A and B above rated speed below rated speed None of these both A and B ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The counter (or back) emf in a dc machine is 1. the same as generated emf in a dc motor 2. proportional to field flux and armature speed 3. not the same as generated emf in a dc motor 4.inversely proportional to field flux 5. proportional to number of armature conductors 6. constant from no load to full load From these, the correct answer is 1, 2, 5 2, 3, 6 2, 4, 5, 6 3, 4, 5 1, 2, 5 2, 3, 6 2, 4, 5, 6 3, 4, 5 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines In a 3 - Φ wound rotor induction motor the short circuit gear is used to short circuit the None of these stator phases of the motor. starting resistance in the starter. rotor at slip rings. None of these stator phases of the motor. starting resistance in the starter. rotor at slip rings. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines In a seperately excited DC Motor if field current is increased, it will Increase acceleration duration. Reduce starting torque. Increase speed Reduce armature heating. Increase acceleration duration. Reduce starting torque. Increase speed Reduce armature heating. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A voltmeter gives 120 oscillations per minute when connected to the rotor of an induction motor. The frequency is 50Hz. The slip of the motor is 2% 4% 5% 25% 2% 4% 5% 25% ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A 4 pole wave wound dc motor having flux per pole of 9.56 X 10-3 Wb contains 460 armature conductors. Calculate the back emf produced when it is running at a speed of 1500 rpm. 240 volt. 220 volt. 440 volt. 230 volt. 240 volt. 220 volt. 440 volt. 230 volt. ANSWER DOWNLOAD EXAMIANS APP
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